Energy relationships

Photosynthesis

Photosynthesis is a very importance reaction for Global let’s how to process photosynthesis from following points

                   •   Choloroplasts as the site of photosynthesis, its fine structure, thylakoids, grana and

                    stroma.

                   •   Pigments associated with absorption of light energy. Absorption spectrum of a pigment.

                    Compare with action spectrum of photosynthesis.

                   •   Mechanism of photosynthesis highlighting following points

                    •   Light reactions

                    •   Dark reactions

                    •   Light reactions

                      

                      •    Photosystems I and II. Antenna complex, excitation of pigment molecules,

                          resonance transfer of energy between pigment molecules. Reaction center

                          molecules, electron transport, photolysis of water, noncyclic and cyclic

                          photophosphorylation, synthesis of NADPH and ATP.

                    •   Dark reactions

                      •    Explain  with following details  which takes place in stroma.

                      •    Calvin cycle of reactions has three stages.

                      •    Carboxylation –CO₂  fixation- RuBP as CO₂  acceptor. RuBP carboxylase enzyme.

                                          

                          Formation of PGA.

                      •    Reduction of PGA, with the use of ATP and NADPH produced in light reaction.

                          Formation of PGAL. Part of PGAL formed is used in synthesis of organic food.

•    Regeneration of RuBP. Part of PGAL formed is used to produce RuBP, using

                          ATP.

                    •   Photorespiration  ,Combining of RuBP with oxygen to produce 1 PGAL (C3) and

                      Phospho Glycolic Acid (C2).Thereby reducing the efficiency of photosynthesis

                    •   Explain the C4 mechanism of CO₂  fixation. It takes place in two stages in two

                                                       

                      different types of cells. Mesophyll cells and bundle sheath cells. PEP as a more

                      efficient CO₂ acceptor, formation of oxaloacetate, malate, its transport through

                                  

                      plasmodesmata, release of CO₂ in bundle sheath cells. Formation of pyruvate and

                                                    

                      return to mesophyll cells. Calvin cycle in bundle sheath cells in a higher

                      concentration of CO₂ .